[liveedit] reimplement frame restarting.

src/interpreter/interpreter-assembler.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/interpreter-assembler.h"
 
 #include <limits>
 #include <ostream>
 
 #include "src/code-factory.h"
@@ skipping 1165 matching lines @@
   Label ok(this), abort(this, Label::kDeferred);
   Branch(WordEqual(lhs, rhs), &ok, &abort);
 
   Bind(&abort);
   Abort(bailout_reason);
   Goto(&ok);
 
   Bind(&ok);
 }
 
+void InterpreterAssembler::MaybeDropFrames(Node* context) {
+  Node* new_fp_address =
+      ExternalConstant(ExternalReference::debug_new_fp_address(isolate()));
+  Node* new_fp = Load(MachineType::TaggedPointer(), new_fp_address);

[jgruber, 2017/01/17 13:29:58]

Is new_fp really a TaggedPointer? Looking at the FrameDropperTrampoline, it
seems like a raw pointer (MachineType::PointerRepresentation()) to me.

[Michael Starzinger, 2017/01/17 14:45:27]

+1, nice catch, I totally missed that!

[Yang, 2017/01/18 07:49:08]

Done.

+  Node* null = IntPtrConstant(static_cast<intptr_t>(0));

[jgruber, 2017/01/17 13:29:58]

Nit: we don't need the static_cast.

[Yang, 2017/01/18 07:49:08]

Done.

+
+  Label ok(this), drop_frames(this);
+  Branch(IntPtrEqual(new_fp, null), &ok, &drop_frames);
+
+  Bind(&drop_frames);
+  // We don't expect this call to return since the frame dropper tears down
+  // the stack and jumps into the function on the target frame to restart it.
+  CallStub(CodeFactory::FrameDropperTrampoline(isolate()), context, new_fp);
+  Abort(kUnexpectedReturnFromFrameDropper);
+  Goto(&ok);
+
+  Bind(&ok);
+}
+
 void InterpreterAssembler::TraceBytecode(Runtime::FunctionId function_id) {
   CallRuntime(function_id, GetContext(), BytecodeArrayTaggedPointer(),
               SmiTag(BytecodeOffset()), GetAccumulatorUnchecked());
 }
 
 void InterpreterAssembler::TraceBytecodeDispatch(Node* target_bytecode) {
   Node* counters_table = ExternalConstant(
       ExternalReference::interpreter_dispatch_counters(isolate()));
   Node* source_bytecode_table_index = IntPtrConstant(
       static_cast<int>(bytecode_) * (static_cast<int>(Bytecode::kLast) + 1));
@@ skipping 107 matching lines @@
     Goto(&loop);
   }
   Bind(&done_loop);
 
   return array;
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8